When using `#fetch` to assign a default value, the default can be passed either as an argument or as a block.
**What are the implications for choosing one approach over the other?**
```ruby
# Option 1: block
setting = settings.fetch('key') { default_setting }
#Option 2: argument
setting = settings.fetch('key', default_setting)
```
When the default value is passed as a block, it is only evaluated when needed (lazy evaluation).
The argument approach could lead to serious performance issues if the default is an expensive operation.